1. Field of the Invention
The present invention relates generally to a scanning imaging device for deployment in either terrestrial or extraterrestrial atmospheres, and more particularly pertains to a simple device in which no moving parts or propulsion systems are employed to impart a rotational motion to the device necessary for the scanning operation.
2. Description of the Prior Art
Reconnaissance of an area is often most efficiently accomplished via an aerial view. The necessary optical or electronic, or electro-optic equipment, is either lifted over or trajected across the territory to be surveyed. Aircraft, missiles and satellites normally fulfill such functions.
Similar reconnaissance of extraterrestrial expanses such as the surface of Mars or Venus considerably complicates matters. The compounding energy requirements demand absolute minimization of the weight of such a device. In addition, the technical complexity required for controlling a device at such distances is staggering. Probes in the past have either been flown by such targets, placed in an orbit, or have been hard-landed or even soft-landed on the surface. The weight and complexity of such programs increases geometrically as one progresses from a fly-by to a soft landing.
There are inherent disadvantages associated with such approaches. The fly-by spacecraft typically passes by the target planet at a considerable distance and at very high speed, thereby allowing only an image of low resolution to be acquired. An orbiting probe can more closely approach atmosphere fringe zones, but the speeds required to stay in orbit are considerable, and for long-lived orbiters contact with the atmosphere is preferably avoided. A probe in orbit is still usually substantially above the surface, diminishing the resulting ability of the imaging device to provide a high resolution image. In addition, some sort of controlling device is required to keep the image detector aimed at the surface and perhaps additionally performing a scanning motion. Hard-landed probes, while perhaps affording a closer view of the surface, have the inherent disadvantage that the time period in which the atmosphere is traversed or until the probe is destroyed is extremely short. Soft-landed probes offer the most potential as far as generating a detailed image is concerned.
A further consideration is the manner in which an image is generated. The tradeoffs betwen a wide angle low resolution view and a narrow angle high resolution view would dictate a composite of a plurality of narrow angle high resolution views. Such an approach requires scanning of the image, and necesarily adds complexity to the probe. Movement of the probe or movement of the detector within the probe is thereby required. The technical complexity of sending such a probe such a large distance and then causing it to scan as it descends adds up to a very complex system.
Similar problems of weight, control and technical complexity are also inherently associated with reconnaissance of the earth's surface. Such terrestrial probes can benefit from the same breakthroughs and improvements imparted to extraterrestrial probes.